1. Field of the Invention
The present invention relates to a digital frequency synthesizer receiver. More specifically, the present invention relates to such a radio receiver employing a storage for storing information concerning a broadcasting frequency signal.
2. Description of the Prior Art
Radio receivers of the digital frequency synthesizer type have been proposed and put in practical use. Briefly, a digital frequency synthesizer radio receiver is structured to obtain a local oscillation signal from a phase locked loop. A phase locked loop typically comprises a reference oscillator the oscillation frequency of which is f.sub.r, a voltage controlled oscillator for providing an output signal the frequency of which is f.sub.o, a frequency divider for dividing the output from the voltage controlled oscillator at the rate of frequency division of 1/N, a phase comparator for comparing the output from the reference oscillator and the output from the frequency divider, and a low pass filter for filtering the voltage signal proportional to the phase difference between the reference oscillator output and the frequency divider output for feeding back the filtered direct current output to the voltage controlled oscillator, whereby in a stabilized or locked state of the above described feedback loop the relation between the oscillation frequency f.sub.o of the voltage controlled oscillator and the oscillation frequency f.sub.r of the reference oscillator becomes f.sub.o =N.multidot.f.sub.r. Thus, in a conventional frequency synthesizer radio receiver, for the purpose of varying the local oscillation frequency, control is accomplished to vary the rate of frequency division by the frequency divider. The frequency divider to be employed for that purpose is normally called a programmable counter.
In a conventional digital frequency synthesizer radio receiver, a scanning operation of receiving frequencies was achieved by providing a scan counter in parallel with a programmable counter such that the scan counter is supplied with a scanning pulse. Since the contents in the scan counter are sequentially changeable upon application of a scanning pulse to the scan counter, the contents in the programmable counter are changed responsive to the output from the scan counter, whereby the rate of frequency division by the programmable counter is changed accordingly.